• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.474-482
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• 2002

The purpose of the study is to establish an optimum geometry and optimum geometry factor through bond test of a structural synthetic fiber, which fully utilizes matrix anchoring without fiber fracturing with the maximum pullout resistance. Seven deformed structural synthetic fibers with widely different geometries were investigated and pullout test was conducted. Included parameters are seven different types of fiber and two of mortar matrixes. The test result shows that the crimped type structural synthetic fiber is significant improvement in the interface toughness(pullout energy) and pullout load. The pullout test was performed with various size of crimped type structural synthetic fiber in order to invest optimum geometry factor, In the basis of the test results, optimum geometry factor is established such as D=b$^{{\alpha}0{\alpha}}$h$^{λ{\beta}}$.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.256-261
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• 2011

A new series of bis acetylated hybrid pyrazoles were synthesized and characterized by their melting point, elemental analysis, MS, FT-IR, one-dimensional $^1H$, and $^{13}C$ NMR spectroscopic data. All the synthesized compounds were tested for their in vitro antifungal activities against Candida sp. namely Candida albicans, Candida glabrata, Candida parapsilosis, Candida dubliniensis and Candida tropicalis. A close inspection of the in vitro anticandidal activity profile in differently electron donating ($CH_3$ and $OCH_3$) and electron withdrawing (-F, -Cl, and Br) functional group substituted phenyl rings of novel hybrid pyrazoles exerted strong anticandidal activity against all the tested Candida species.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.409-411
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• 2017

미사일 추력기 체계에 적용되는 하이드라진[$N_2H_4$]추진제는 MSDS-OHS 유해성 분류상 급성독성 물질로서 사용이 제한되고 있는 바, 다양한 대체물질이 개발 중이다. 최근 해외에서 안전성과 취급이 우수한 질산 히드록실암모늄[$NH_3OHNO_3$]과 암모늄 디나이트라마이드[$NH_4N(NO_2)_2$] 기반 단일계 액상추진제가 개발중이며, 이 물질들을 이용한 추력기 시스템 적용 시험이 진행되고 있다. 그러나 저온에서의 연로물질 산성화 반응으로 인한 디나이트라마이드[$N(NO_2)_2{^-}$] 물질의 분해는 나이트레이트[$NO_3{^-}$] 이온 생성을 촉진시키며, 부수적으로 발생하는 침전물은 촉매 및 노즐의 막힘 현상을 유발하므로 추력기 성능의 저해요인으로 작용한다. 그러므로 저온분해 방지를 위한 첨가제 조성 개발 및 열분해 특성 연구가 최근의 관심사이다. 본 연구는 합성/정제/추출한 암모늄 디나이트라마이드 산화제를 주요 조성물로 적용하였으며, 염기성 안정화제를 질량비율 4~5% 첨가하여 산성화 반응을 억제시킨 단일계 액상추진제(KMP) 형태로 제조하였다. 합성한 추진제는 시차주사열량계(DSC)를 이용하여 분해온도를 측정하여 열안정성을 평가해보았다.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.566-575
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• 2008

We investigated the field emission characteristics from the planar field emitters made of double-walled carbon nanotubes (DWCNTs) synthesized by a catalytic chemical vapor deposition (CCVD) method. Transmission electron microscopy, Thermogravimetric and Raman analysis showed that the carbon materials have a low defect level in their atomic carbon structure, pointing to the synthesis of high-purity DWCNTs. For field emission properties of DWCNTs, the turn-on field of DWCNTs was $1.9\;V/{\mu}m$ and the current density was about $74\;mA/cm^2$ at $8.1\;V/{\mu}m$, which is sufficient for the applications of field emission displays and vacuum microelectronic devices. The DWCNT field emitters also exhibited a uniform field emission pattern and good field emission stability in a diode configuration.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.264-268
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• 2007

The filtration performance of micron-sized metal fibrous filter was improved by synthesizing carbon nanotubes grown on the surface of metal fibers. The carbon nanotubes are grown with bush-like nanostructures covered around the micron-fibers or web-like nanostructures crossing between the fibers at different synthetic conditions. Filtration efficiency of CNT-metal-filter was measured and compared with the efficiency of the raw metal filter without CNTs. The developed CNT-metal-filter has higher filtration efficiency without significant difference in pressure drop compared with the conventional metal filter, which is because the carbon nanotubes function as the trap of pollutant nanoparticles.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.56-67
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• 1999

In this paper, the new composition Irethod of global and local fuzzy reasoning concepts is proposed to reduce, optimize and automatically acquire the number of rules, without any lose of the general performances in conventional fuzzy controllers. In order to control the interaction between global reasoning and local reasoning, the DNA coding algorithm is introduced to the local fuzzy reasoning of the proposed composition fuzzy reasoning rrethod. The method is awlied to the real liquid level control system for the purpose of evaluating the performance. The sinru1ation results show that the proposed technique can control the system with higher accuracy and automatical1y acquire the fuzzy rules with rmre feasibility, than the conventional methods.ethods.

• Polymer(Korea)
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• v.33 no.1
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• pp.67-71
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• 2009

The stitching method for the synthesis of $Fr\acute{e}chet$-type dendrimers was elaborated using click chemistry between an alkyne and an azide. The core building block, 4,4'-(3,5-bis(azidopropyloxy)benzyloxy)bisphenyl, was designed to serve as the azide functionalities for dendrimer growth via click reactions with the alkyne-dendrons. The synthetic strategy involved an 1,3-dipolar cycloaddition reaction between an azide and an alkyne-functionalized $Fr\acute{e}chet$-type dendrons in the presence of Cu(I) species which is known as the best example of click chemistry.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.282-286
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• 1992

The reaction of N-hydroxysuccinimide with polyacrylic acid and polymethacrylic acid gave poly(N-acryloxysuccinimide)and poly(N-methacryloxysuccinimide), whose reaction with cephradine provided polyacryloylcephradine and polymethacryloylcephradine. The activities of these polymeric drugs were investigated in terms of minimum inhibitory concentration by the common twofold dilution technique. Polyacryloylcephradine revealed excellent antibacterial activity against Staphylococcus aureus ATCC 25923, Staphylococcus aureus FDA 209P, Bacillus subtilis ATCC 6633, Bacillus licheniformis ATCC 14580, Escherishia coli BE 1186 and Salmonella typhimurium TV 119. Polymethacryloylcephradine revealed excellent Staphylococcus aureus ATCC 25923, Staphylococcus aureus FDA 209P, Bacillus subtilis ATCC 6633, Escherichia coli Be 1186 and Salmonella typhimurium TV 119.

• Journal of agriculture & life science
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• v.43 no.4
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• pp.15-20
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• 2009

The transition from pregnancy to lactation, commonly referred to as the "transition period" is characterized by dramatic changes in metabolic processes and their regulation in order to prepare the dairy cow for parturition and lactogenesis. An important adaptation to lactation is the increase in gluconeogenesis by the liver to meet the tremendous increase in demand of glucose for lactose synthesis, and the accumulation of lipid in adipose tissue during pregnancy, its mobilization that begins prior to lactation and the dramatic increase in plasma NEFA concentration early lactation. Epinephrine and insulin, the homeostatic regulators of metabolism are responsible for the adaptations of lipid and carbohydrate metabolism in support of milk production along with mobilization of body fat to meet overall energy demands because dry matter intake is insufficient to meet these demands during early lactation.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.152-156
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• 2019

The removal property of magnetic zeolite for the adsorption of aqueous ammonium ion was examined in this work. The surface modified magnetic zeolite was produced by hydrothermal synthesis. The complex of zeolite and $Fe_3O_4$ was established by the observation of SEM and XRD analysis and less than 12.6% of $Fe_3O_4$ content in magnetic zeolite was observed in the form of $Fe_3O_4$ particles. The optimum pH of adsorption was shown around 8 and the maximum adsorption linearly decreased with the increase of $Fe_3O_4$ content. The adsorption isotherm for aqueous ammonium ion was approximated by Langmuir equation. The developed surface modified magnetic zeolite adsorbent was recommended to control the nitrogen pollution for wetland environment system.